The microfluidic device uses antibodies to "capture" white blood cells called T cells that are affected by HIV. In addition to physically binding these cells the test detects the types and levels of inflammatory proteins (cytokines) released by the cells.

Professor Revzin's team at the University of California, Davis, collaborated with UCLA electrical engineer Professor Aydogan Ozcan to integrate an antibody microarray with a lensfree holographic imaging device that takes only seconds to count the number of captured cells and amount of secreted cytokine molecules. The test returns results six to twelve times faster than traditional approaches and tests six parameters simultaneously, based on a small blood sample.

With further refinements, the test will have wide potential use for multi-parametric blood analysis performed at the point of care in the developing world and resource-poor areas. Its affordability will also make it an attractive option in wealthier areas. Revzin has filed for a patent and is looking for ways to bring his test into clinical use.

"In addition to HIV testing and monitoring, this device will be useful for blood transfusions, where the safety of blood is frequently in question," Revzin says.

The most accurate and effective way to diagnose and monitor HIV infection involves counting two types of T-cells, calculating the ratio between the two types of T-cells, and measuring cytokines. Scientists do this using a method called flow cytometry that requires an expensive machine and several highly trained specialists. Healthcare workers and AIDS activists in the developing world have called for less expensive, more easily performed tests.

"While the point of care field focuses on detection of single parameter (e.g. CD4 counts), we believe that the simplicity of the test need not compromise information content. So, we set out to develop a test that could be simple and inexpensive but would provide several parameters based on a single injection of a small blood volume," explains Revzin.

Ozcan's lensfree on-chip imaging allowed the scientists to rapidly image and count T-cell arrays without the use of any lenses or mechanical scanning. Analysis of CD4 and CD8 T-cell numbers, the CD4/CD8 ratio and three secreted cytokines took only seconds.